Active Traffic Management (ATM) strategies provide the “ability to dynamically manage recurrent and non-recurrent congestion based on prevailing and predicted traffic conditions” (FHWA’s Active Traffic Management website). New traffic control devices and approaches are needed to support these strategies and many of those devices and approaches are not included in the MUTCD. Furthermore, the effectiveness of the devices and approaches in obtaining the desired response from drivers are not well understood. Inefficiencies in traffic control lead to reductions in safety and operational efficiency, precisely what ATM is intended to improve.
One of the commonly used ATM strategies is dynamic lane use control. The FHWA defines dynamic lane use control as dynamically closing or opening individual traffic lanes as warranted and providing advance warning of the closure(s) (typically through dynamic lane control signs), in order to safely merge traffic into adjoining lanes. Drivers are required to identify and understand the intended lane usage and make an appropriate maneuver safely and smoothly.
In many existing dynamic lane use control installations, acceptable travel lanes are identified by text-based or graphical overhead signage such as a green arrow or a dynamic speed limit sign. Closed travel lanes are most often identified by an overhead red ‘X’. In some locations, ground-mounted signing is also used to communicate lane use to drivers. For example, Seattle, WA uses shoulder- or barrier-mounted signs that read either SHOULDER OPEN TO TRAFFIC or SHOULDER CLOSED. Other locations use signs to indicate the type of traffic allowed in the controlled lane (frequently buses). Various forms of static pavement marking or colored pavements are used to support the signs. There is little consistency and limited guidance in the methods used for communicating dynamic lane use control to drivers and little research on the most effective approaches. There are a number of other operational strategies that present similar traffic control challenges and the traffic control approaches should be consistent.
The objective of this research was to develop recommendations for the application of dynamic lane use control based upon their human factors implications. This research discovered how dynamic lane use control should be interpreted broadly so as to include applications such as reversible lanes, hard shoulder running, dynamic junction control, and toll plazas.
This project is complete and the final report has been published as NCHRP Research Report 1021, "Application of Dynamic Lane-Use Control: Proposed Practices."